The decomposition of methanol on the Ni(1 1 1) surface has been studied with the pseudopotential method of density functional theory-generalized gradient approximation (DFT-GGA) and with the repeated slab models. The adsorption energies of possible species and the activation energy barriers of the possible elementary reactions involved are obtained in the present work. The major reaction path on Ni surfaces involves the O-H bond breaking in CH3OH and the further decomposition of the resulting methoxy species to CO and H via stepwise hydrogen abstractions from CH3O. The abstraction of hydrogen from methoxy itself is the rate-limiting step. We also confirm that the C-O and C-H bond-breaking paths, which lead to the formation rate-limiting of surface methyl and hydroxyl and hydroxymethyl and atom hydrogen, respectively, have higher energy barriers. Therefore, the final products are the adsorbed CO and H atom.